OBJECTIVE: To solve selected key technical problems in radiation therapy that limit the effectiveness of present treatment: a) to design, build and evaluate an instrument system for measurement of anatomical inhomogeneities in radiotherapy patients. b) To develop a human engineered minicomputer system for improved display and three dimensional treatment planning. C) To control multiple parameters such as couch position, gantry angle, collimator opening, and beam intensity during treatment using a minicomputer. APPROACH: Currently available computer technology is being applied to the solution of these specific radiation therapy problems in obtaining more optimal dose distribution. The evaluation of anatomical inhomogeneities is by means of multiple linear scan reconstruction technique with an No. I detector and 1MeV photons.